Process of manufacturing parchment-paper



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UNITED STATES PATENT OFFICE.

WALTER DAGNALL, 0F HAMPTON WICK, ENGLAND.

PROCESS OF MANUFACTURING PABCI-IMENT-PAPER.

Title librawing.

sulfurous acid of different strength, viz. the first bath with sulfuricacid and Water 1 of a specific gravity of 1.700 to 1.800 to which isadded sulfurous acid to reduce it until it registers 1.750 and thesecondbath, of which the sulfuric acid is of the same strength but thesulfurous acid is admixed in greater quantity to reduce it to a specificgravityvarying from 1.200 to 1.400, all solutions losing at aloout 60%F., the strength of the acid varying according to the quality andtexture of the paper I wish to impregnate or parchmentize, i. e. thethicker the paper, the greater the strength of acid required. Then thepaper is Washed and afterward passed throughan alkali bath and againwashed and softened in any lrnown manner either by glycerin, calciumchlorid, salt, or thelike. In this latter process the paper or parchmentma be loaded with any suitable materia or mineral earth.

In carrying my invention into'practice the paper is first run or passedfrom the reel into the first acid bath which is kept cool. It is thensqueezed and the surplus acid returned to the first bath, it is thenpassed under rollers to the second bath (which is likewise kept cool,)squeezed between rollers, and the surplus acid returned to the secondbath, care being taken that the specific gravity of the acid in thesebaths in in conformity with the limits aboveetated. It is essential thatthe acid baths do not rise above 60% F. since this would deteriorate thepaper. The paper is then passed between water sprays and well washed toremove the acid, is then passed between rollers and squeezed, and thenpassed through an alkali bath to remove IIBSSBS.

Specification of Letters-Patent. Patented Mar. 23, 1920.

Application filed February 4, 1919. Serial 1 Io. 275,006.

any remaining acid that may be left in. The paper is then passed betweenrollers and squeezed .and again passed through water sprays and thenbetween rollers and squeezed and then, if required, through thesoftening bath of glycerin, calcium chlorid,

salt, or the like (which latter bath may be heated by a steam coil). Thepaper is then squeezed again between rollers and finally a dried,

calendered and cut up ready for marke By my invention the papers may bemore thoroughly and quickly treated and at the same time thoroughlyparchmentized, hence a greater quantity can be parchmentized Within agiven period than by known processes, which makes it more economical andhence cheaper to work and the parchment paper is of superior qualitybecause of its not being brittle.

What I do .claim as my invention, and desire to secure by LettersPatent, is

1. Process of treating paper to render it like parchment, andwaterproof, acid proof and ofgreat strength, consisting in' passingpaper through a bath of sulfuric acid gravity of from 1.700 to 1.7 50,squeezing the paper after leaving sald bath, t en passin the paperthrough a loath'of sulfuric i101 and water of specific gravity of 1.800reduced by sulfurous acid to a specific gravity of from 1.200" to 1.400at 60 F., and then again squeezing, the paper.

In testimonywhereof I have hereunto setv my hand in" presence of twosubscribing wit- WALTER DAGNALL.

Witnesses:

J. M. Bnn'rrrunor,

WM. A. Brown.

. of specific gravity of 1.800 admixed with Q 'sulfurous acid -to reduceto a specific

